1. Field of the Invention
The present invention relates generally to a Location Based Service (LBS) system utilizing terminals, and in particular, to a LBS system for providing location information of a target terminal for positioning.
2. Description of the Related Art
In conventional LBS systems, when one of a child's parents requests location information of his/her child to a LBS provider, the LBS provider does not provide the other parent with the location information. That is, in order to be provided with the location information of her/his child, the other parent must separately request the location information to the LBS provider. A user of a target terminal for positioning wants his/her location information to be provided only to those who obtain his/her own permission. This can be achieved through an authentication process for privacy security. A LBS provider provides location information of a target terminal only to a person who requests the location information. Therefore, when a third party wants to know the location information of the same target terminal, he/she must separately request the location information from the person having previously requested the location information from the LBS provider.
FIG. 1 is a timing chart illustrating a conventional LBS procedure.
A client, for example, a Secure User Plane for Location (SUPL) Agent 10, requests location information to a Home SUPL Location Platform (H-SLP) 20 by transmitting a Mobile Location Protocol (MLP) Standard Location Immediate Request (SLIR) message containing its own identifier (client-id) and an identifier (ms-id) of a target terminal for positioning (Target SET) 30 to the H-SLP 20 in step S10. Using the ms-id, the H-SLP 20 determines whether the terminal 30 is roaming in step S20, and transmits a SUPL INIT message, which informs the terminal 30 of the start of the positioning, to the terminal 30 in step S30. Here, the H-SLP 20 uses a Wireless Application Protocol (WAP) Push or Short Message Service (SMS) Trigger method for transmitting the SUPL INIT message to the terminal 30. The H-SLP 20 generates a session-id so as to discern data communication with the terminal 30, and then contains the session-id in the SUPL INIT message. The H-SLP 20 also contains a parameter indicating a positioning method (posmethod) used therein and whether the H-SLP 20 is set up as one of a proxy mode and a non-proxy mode. A difference between these two modes is that the H-SLP 20 is divided into a management server and a calculation server in the proxy mode, and is integrally formed in the non-proxy mode.
While receiving the SUPL INIT message from the H-SLP 20, the terminal 30 attempts data connection to the H-SLP 20 (S40), and permits the positioning of the target terminal 30 by transmitting a location id (lid), which indicates information on a network where the terminal 30 is presently located and a positioning method of the terminal 30 (SET capability), to the H-SLP 20 in step S50. The H-SLP 20 determines the SET capability of the terminal 30 and its own pos-method. Using these methods, the H-SLP 20 transmits/receives data necessary for the positioning to/from the terminal 30 in step S60. Either the H-SLP 20 or the terminal 30 determines a final location result (pos-result). The H-SLP 20 then transmits a SUPL END message to the terminal 30 to signal the terminal 30 of the ending of the corresponding positioning session in step S70. The H-SLP 20 transmits the pos-result to the SUPL Agent 10 in step S80.
According to FIG. 1, the pos-result is provided only to the SUPL Agent 10. That is, one request for location information results in only one location information transmission. Consequently, if there are a number of requesters for location information of the same terminal, a problem occurs in that the respective requesters must separately transmit MPL SLIP messages to the H-SLP 20.